1. Field of the Invention
The present invention relates to a disk drive unit, and more particularly to a method of controlling the positioning of a magnetic head of the disk drive unit and to the disk drive unit executing the same, whereby power consumption during the time from which the power is turned ON to the realization of the unit ready state can be shortened by controlling the positioning of the magnetic head of the disk drive unit.
2. Description of the Related Art
When the power supply thereto is turned ON, the magnetic disk drive unit starts to rotate a disk thereon, and when the rotation speed has reached a certain level, the magnetic head is made to float above the surface of the disk. When the power supply is turned OFF and the speed of rotation of the disk is reduced, the magnetic head is allowed to again come into contact with the surface of the disk.
Accordingly, because when the disk is first rotated the magnetic head is in contact with the surface of the disk, at that time the magnetic head is positioned at an evacuating area called a contact start stop (CSS) area, provided on the disk. Then, when the disk reaches a predetermined speed of rotation after the power supply thereto is turned ON, the magnetic head floating above the CSS area is initially moved to a position on a 0 cylinder corresponding to the outer most tracks of each disk, and when this positioning on the 0 cylinder is completed, the unit is in a ready state and waits for an instruction from a host apparatus.
If the unit is given a power OFF instruction while the magnetic head is positioned above the CSS area, when the power is turned OFF the rotation of the disk is stopped and thus the magnetic head is brought into contact with the CSS area. The above operation must be carried out to ensure that the magnetic head does not rub against the data storage areas of the disks. Note, data is not stored in the CSS areas.
After the power is turned ON and before the initial seeking movement thereof, if the magnetic head is moved from the CSS area to the data storage areas, the servo head approaches an area in which the servo information is stored and reads noise. If this noise is supplied to a seeking control circuit, the initial seeking movement of the magnetic head cannot be carried out in a normal manner. Further, since the servo head is in contact with the disk surface at the CSS area, when the rotation of the disk is started, the servo head is sometimes moved to the data storing area while rubbing against the disk surface, and thus the servo head frequently reads noise.
Therefore, the magnetic head must be positioned on the CSS area during the time from the turning ON of the power to the start of the initial seeking movement thereof. This positioning of the magnetic head as mentioned above increases the power consumption.
Namely, in a conventional unit, when the power supply to the magnetic disk drive unit is turned ON, since a motor driving a carriage is continuously supplied with electric current until just before the start of the initial seeking movement, a problem arises in that the power consumption is increased, and simultaneously, the temperature of the magnetic disk drive unit is elevated by heat radiated by a power amplification circuit or the like when the power ON or OFF operations for the magnetic disk drive unit are repeated.